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THE CHEMISTRY 



COOKING AND CLEANING 

A MANUAL 'for HOUSEKEEPERS 



ELLEN IL RICHARDS 

Instructor in Chemistry, Woman's Laboratory, 

Massachusetts Institute of Technology, 

Boston 



BOSTON 
ESTES & LAURIAT 

301 — 305 WASHINGTON ST 



1542) 



Copyright, 1881. 
BY ESTES iL LAURIAT. 



TX 



PREFACE. 



TN this age of applied science, every opportunity 
of benefiting the household should be seized 
upon. 

The family is the heart of the country's life, and every 
philanthropist or social scientist must begin at that 
point. Whatever, then, will enlighten the mind, and 
lighten the burden of care, of every housekeeper will be 
a boon. 

At the present time, when the electric light and 
the gas stove are familiar topics, there is, after all, no 
branch of science which might be of more benefit to 
the community, if it were properly understood, than 
Chemistry — the Chemistry of Common Life. John- 
ston's excellent book with that title deserves a wider 
circulation, and a more careful studjr. 



viii PREFACE. 

But there is a space yet unoccupied for an elemen- 
tary work which shall give to non-scientific readers 
some practical information as to the chemical com- 
position of articles of daily use, and as to their action 
in the various operations in which they are employed. 

The public are the more ready for the application 
of this knowledge since Chemistry is taught in nearly 
all High Schools, and every child has a dim idea of 
what some part of it means. To gather up into a 
definite and practical form these indistinct notions is 
the aim of this little book. 

There is, lingering in the air, a great awe of chem- 
istry and chemical terms, an inheritance from the age 
of alchemy. Every chemist can recall instances by 
the score in which manufacturers have asked for 
recipes for making some substitute for a well-known 
article, and have expected the most absurd results to 
follow the simple mixing of two substances. Chemicals 
are supposed by the multitude to be all-powerful, and 
great advantage is taken of this credulity by unscrupulous 
manufacturers. 

The number of patent compounds thrown upon the 
market under fanciful and taking names is a witness 



PREFACE. Ix 

to the apathy of housekeepers. It is time that they 
should bestir themselves for their own protection. A 
little knowledge of the right kind cannot hurt them, 
and it will surely bring a large return in comfort and 
economy. 

These mysterious chemicals are not so many or so 
complicated in structure but that a little patient study 
will enable any one to understand the laws of their 
action, as far as they are concerned in the common 
operations of the household. 

No attempt is here made to cover the whole ground 
of chemical science, but only to explain such of its 
principles as are involved in the raising of bread, and 
in a few other common processes. 



CONTENTS. 



Chap. PAr.K. 

I. Introduction, , , r 

II. Starch. Sugat, and Fat, as Food. . i6 

III. Nitrogenous Food and the Chemistry 

OF Nutrition, . . . '*. . -37 

PART II. 

I. The CntLMisTRY of Cleaning, . . -55 

II. Chemic.\ls for Household Use, . . .80 



CHAPTER I. 



INTRODUCTION. 



T^T'E recognize substances, as we know people, 
by their characters (properties) and by 
their appearance. Sugar we call sweet ; if any- 
'thing is sour/ we call it acid. Sugar and salt 
dissolve in water. Carbonic acid gas will extin- 
guish the flame of a candle. These are proper- 
ties of the several substances. A teaspoonful of 
sugar heated over a fire turns black, swells up 
to a large bulk, emits a gas which, burns with a 
smoky flame, and finally there is left a black, 
crumbly mass, which seems like what it is, fine 
charcoal. There is nothing which we consider 
su;;ar left, no sweetness, none of the properties 
vvhich we know under the name of sugar. There 



2 THE CHEMISTRT OF 

is a change, a loss of identity. This change is 
called a chemical one. 

Add a solution of an acid to a solution of 
an alkali, and observe that the acid substance and 
the alkaline substance are no longer in existence 
as such. There is, instead, a neutral saline sub- 
stance dissolved in water. The new substance 
has not the properties of either of the others. 
The acid and the alkali have both lost their 
identity. A chemical change, then, involves a loss 
of identity. 

" We must be very careful not to transfer our 
ideas of composition, drawn chiefly from the mix- 
tures we use in common life, directly to chem- 
istry. In these mixtures the product partakes, to 
a _^reater or less degree, of the character of its 
constituents, which can be recognized, -essentially 
unchanged, in the new material. In all instances 
of true chemical union and decomposition, the 
qualities of the substances concerned in the pro- 
cess entirely disappear, and wholly different sub- 
stances with new qualities appear in their place."* 

* "The New Chemistry." — Josiah P. Cooke. /. 99. 



COOKING AND CLEANING. 3 

All the substances about which we know any- 
thing are composed of a few elementary bodies. 
The grain of wheat, the flesh of animals, the 
dangerous poison, all are capable of being sep- 
arated into the simple substances of which they 
are composed. The chemical element is that 
substance out of which nothing essentially differ- 
ent* has ever yet been obtained. Pure gold is 
an element, a simple substance, from which nothing 
can be taken different from itself. A gold coin 
contains a little copper or silver, or both, and is 
not pure gold ; it is a mixture of two or more 
elementary substances. The oxygen in the air is 
an element, a single thing. Water is a compound 
of two elements, oxygen and hydrogen, which are 
gases when they exist as simple substances. 

There are about seventy of these elementary 
substances known to the chemist ; about ten or 
twelve of them enter into the compounds which 
we use in the kitchen. The others are found only 
in the chemical laboratory or in the physician's 
medicine case, and a few are so rare as to be 

* "Treatise on Chemistry." — Roscoe & Schorlemmer. p. 51. 



4 THE CHEMISTRY OF 

considered curiosities. Most of these elements 
unite with each other, and, in the compounds thus 
formed, other elements may exchange places with 
those already there, so that a few elementary 
bodies, by the variety of combination, make up 
the objects of daily use. 

To understand something of the nature of these 
chemical substances and their common forms is 
a necessity for every housekeeper who would not 
be cheated of her money and her time. 

It is important for every one to remember that 
laws govern all chemical changes; for one is often 
asked to believe that some chemical sleight of hand 
can make one pound of washing-soda worth as 
much as two, and that some special preparation 
of flour will give a third more bread than any 
other. 

As has been said, we recognize substances by 
their properties, and the chemical elements have 
two essential characteristics vvhich must be con- 
sidered at the outset of our discussion. 

It is assumed that they are composed of homo- 
geneous, particles, the so-called atoms, the smallest 



COOKING AND CLEANING. 5 

masses of matter which enter into chemical com- 
bination. The particles have a definite weight, 
constant for each substance. This weight is known 
in chemistry as the atomic weight. 

Hydrogen being the lightest substance yet known, 
its atomic weight is taken as the unit. 





TABLE I. 




NAME. 


SYMBOL. 


ATOMIC WEIGHT. 


Hydrogen 


H 


I 


Sodium (Natrium) 


Na 


33 


Calcium 


Ca 


40 


Oxygen 


O 


16 


Carbon 


C 


12 



The atom of oxygen weighs 16, and the atom of 
calcium 40 times as much as the atom of hydrogen. 
The letters or symbols in chemical formulae rep- 
resent this definite weight, so that while the word 
oxygen means only that collection of properties 
to which we give the name, the letter O in a 
formula indicates also 16 times the weight of H, 
which is taken as i. 

These symbols give a definiteness to the chemical 



6 THE CHEMISTRr OF 

terms which words merely cannot convey, and 
therefore they are a great aid to the right com- 
prehension of the laws of combination. In a table 
at the end of the book will be found the atomic 
weight of all the elements referred to in the text. 

The atoms of each element have also their own 
value in uniting and exchanging places with the 
others. 

The unit of value is an arbitrary standard. Some- 
thing else might have been taken than the unit 
chosen, but the relative value of all the elements 
as compared wiih each other is constant. 

At the outposts of the Hudson's Bay Territory 
all trade is on a system of barter or exchange, and 
a basis of value is necessary. The skin of a beaver 
is agreed upon as the unit from which to count 
all values. For example : a red fox skin is worth 
two beaver skins, a silver fox skin is worth 
four beaver skins. All of the hunter's stock is 
valued in tliis way, and also articles to be purchased 
are valued by the same standard, a knife is pur- 
chased for four beaver skins, a gun is worth three 
silver fox or twelve beaver skins. Chemists have 



COOKING AND CLEANING. 7 

agreed upon a unit of value in exchange, and the 
unit thus agreed upon is the atomic weight of 
hydrogen above referred to ; that is, the smallest 
relative weight of hydrogen known to enter into 
combination with other elements. It is, in a sense, 
an arbitrary choice, but having once accepted it 
as the unit, we can count all other values, in union 
or in exchange, from its value. 



TABLE 


//. 










NUMBER 


OF ATOMS OF 






HYDROGEN 






WHICH 


THE ATOM OF 






THE SUBSTANCE WILI, RE- 


NAME. SYMBOL. 


PLACE ; 


IN COMPOUNDS. 


Sodium (Natrium) Na 






I 


Calcium Ca 






2 


Oxygen 






2 


Carbon C 






4 



For the convenience of the reader, this exchange- 
able value will be indicated by the numbers over 
the letters in the formulae given in this book, 
although the practice is not universal. 

The chemist has constructed a sign language, 
based upon these two properties of the elements, 
which aids the mind in grasping the idea of 



8 THE CHEMISTRT OF 

chemical changes. The symbols are, as it were, 
the chemist's alphabet. 

The non-scientific reader is apt to look upon 
the acquisition of this sign language as the 
school-boy regards the study of Chinese — as the 
work of a lifetime. While this view might not 
be so very far from the truth, if one were to 
attempt to remember all the symbols of the com- 
plicated compounds which are possible in the 
union and interchange of the seventy or more 
elements, yet the properties and combinations of 
the dozen of them which make up the common 
substances of daily use are not beyond the reach 
of the busy housewife, and can be comprehended 
in a few hours of thoughtful reading. " To mas- 
ter the symbolical language of chemistry, so as to 
fully understand what it expresses, is a great step 
towards mastering the science."* 

Hydrogen seems to be the connecting link be- 
tween the other elements, which may, for our 
present purpose, be divided into two classes, as 
shown in 

* " 'I'he New Chemistry." /. X49> 



COOKING AND CLEANING, 



TABLE III. 



Some elements 


which can 


Some elements which imite 


be substituted for 


with H, 


and with 


H, and for each other in 


Class I., as 


well 


as with 


chemical compounds. 


each 


other. 






BXCHANGE 






EXCHANGE 




VALtm. 






VALUE. 


Sodium 


I 

Na 1 


Chlorine 




I 

CI I 


Potassium 


K I 


Oxygen 




II 

O 2 


Calcium 


II 
Ca 2 

Hydrogen 


Carbon 

I 
H 1 




IV 

C 4 



I 



I I 



H unites with CI, and forms HCl, or muriatic 
I I 

acid. K exchanges places witli H, and the new 

III II 

compound is KCl. Hj unites with O, and forms 

I II 1 I 
H2O, or water. Kg exchanges places with H2, 

I II IV 

and the new compound is K2O. C unites with 

II IV II 

O2 and forms CO2, carbon dioxide, or carbonic 

IV 11 I II 

acid gas. CO2 unites with H2O, and becom.es 

I IV II I 

H2CO3, or carbonic acid in solution. Nag ex- 

I 
changes places with H2, and the new compound 



10 THE CHEMISTRY OF 

I IV II 
is Na2C03, or commercial soda ash, the compound 

with which the laundress is familiar, under the 

name of washing crystal. 

The letters mean always the smallest relative 

quantity known to combine with anything else, 

and when the elements combine in more than 

one proportion, we indicate it by writing two 

I I 

times or three times the units. Thus H, or 2H 

I 
means twice the unit value of H. 

Some of the compounds formed by the union 
of the elements given in the Tables are very 
familiar substances. 

I ir 

H2O Water. 

I X 2, 16 Two parts by weight of hydrogen. 
Sixteen parts by weight of oxygen. 

I O will unite with 2 H. 

II II 

Ca O Quick-lime. 

40, 16 Forty parts by weight of calcium. 

Sixteen parts by weight of oxygen. 

I Ca will exchange places with 2 H. 
IV II 
C O2 Carbonic acid gas. 

12, 16 X 2 Twelve parts by weight of carbon. 

Thirty-two parts by weight of oxygen. 



COOKING AND CLEANING. i ll 

■ The exchanges and interchanges of the ele- 
ments according to these two laws of value and 
weight are chemical reactions, and the expres- 
sion of them is called a chemical equation. A 
certain modicum of chemical arithmetic is essen- 
tial to the right understanding of these reactions. 

" In the laboratory we never mix our materials 
at random, but always weigh out the exact pro- 
jjortions . . . for, if the least excess 
of one or the other substance over the propor- 
tions indicated is taken, that excess will be wasted. 
It will "not enter into the chemical change."* 

In the economy of nature nothing is lost. The 
wood and coal burned in our stoves do not 
vanisli into thin air, without adding to its weight. 
Twelve lbs. of coal (not counting the ash), in 
burning, take 32 lbs. of oxygen, and there are 
formed 44 lbs. of carbonic acid gas. 

In all chemical equations there is just as much 
in weight represented on the one side of the 
sign of equahty (=) as on the other. 

* "The New Chemistry."' /. 151. 



12 THE CHEMISTRT OF 

For instance, in the equation 

II I I II II 1 II 

HCl + NaHO = NaCl + H^O 

Muriatic Caustic Sodium Water. 

Acid. Soda. Chloride or 

Salt 

36.5 + 40 = 58.5 + 18 
76.5 = 76.5 

The sum of the weights ot the two substances 
taken is equal to the sum of the weights of the 
two new substances formed as the result of the 
reaction. 

The present science of chemistry may be said 
to date from the discovery of the law of definite 
proportions, which gave a firm basis for all cal- 
culations. If we wish to obtain 44 lbs. of car- 
bonic acid gas (carbon dioxide), we can tell 
just how much pure charcoal must be taken, by 
writing out the reaction thus : 

IV I IV 11 
C -f O, = C O. 

The atomic weight of Carbon is 12, X i = 12 
The atomic weight of Oxygen is 16, X 2 = 32 

44 
Therefore 12 lbs. of charcoal must be burned 
in order to obtnin 44 lbs. of carbonic acid gas. 



COOKING AND CLEANING. 13 

This law of definite proportion by weight can- 
not be too strongly emphasized. It is the inva- 
riable rule of chemical action, and it will be 
referred to again and again in discussing the 
chemical changes occurring in cooking and in 
digestion. 

When more than two elements enter into com- 
bination, it is common for two or more to band 
together, and in this case the group h<is an 
exchange value of its own, which is not the sum 
of the values of the separate elements, but which 
is constant, and dependent upon these values in 
a way which it is not necessary to explain here. 

These partnerships will be included in brackets 
II II I 

as (SO^) (CO3) (NO3), not that these letters 

represent actual compounds existing by themselves, 

I II IV II II I 
as do H2O, CO2, CaCi2, but that the group en- 
closed in the brackets passes from one compound 
into another as if it were only one element, and 
the numbers over the bracketed letters will indi- 
cate the exchange value of the partnership, not 
of the elements separately. A few illustrations 
will serve to make this clearer. 



14 THE GHEMISTRT OF 

TABLE IV. 

Mineral Acids and Compounds : 

I I I I I TI I 11 

HCl H(N03) H,(S04) H^CCOs) 

Muriatic. Nitric. Sulphuric. Carbonic 

I I I I II II II II 

NaCl KCNOa) Ca(S04) C*(CO,) 

Salt. Saltpetre. Plaster of Marble. 

Paris. 

Reactions and Equations : 

I II II II 11 II I II 

H,(S04) + Ca(CO0 = Ca(S04) + H^CCOj) 

1 II I I I II II 

H..(S04) + 2(NaCI) = Na.,(S04) + 2(HC1) 

I II II I I II II 

H2(S04) + NaCr =NaH(S04)+ HCl 

It will be seen that the groups do not sep- 
arate, but that they combine with the single 
elements by the same law as that which governs 
the combinations of the simple substances. 

It is also to be observed that where two atoms 

of hydrogen can be replaced in a compound, as 

I II 
in IIo(S04), either one or both can be exchanged 

for an atom of equal replacing value, and the 

two compounds thus formed will differ in their 

properties. This will be shown later on, in the 

case of cream of tartar. 



OF COOKING AND CLEANING. 15 

For a full and clear exposition of the principles 
of the science, the reader is referred to " The 
New Chemistry," by J. P, Cooke. 



CHAPTER II. 

STARCH, SUGAR, AND FAT, AS FOOD. 

"\^7"HEREVER there is life, there is chemical 
change, and as a rule a certain degree of 
heat is necessary, in order that chemical change 
may occur. Vegetation does not begin in the colder 
climates until the air becomes warmed by the 
heat of spring. When the cold blasts of winter 
come upon the land, vegetation ceases. If plant 
life is to be sustained during a northern winter, 
artificial warmth must be supplied. This is done 
by keeping up a furnace or stove heat. In 
chemical terms, carbon from coal, wood, or gas 
is caused to unite with the oxygen of the air to 
form carbonic acid gas, and by this union of two 
elements, heat is produced : 

i6 



COOKING AND CLEANING. 17 

IV II IV II 

C + O2 = C O,. 
In wood and gas there is another compound 
which is utilized : 

IV I II IV II I II 

CH4 + O4 = COi + 2 H2O. 

These two chemical reactions express the changes 
which cause the production of artificial heat used 
for domestic purposes. 

As many animals live in temperatures in which 
plants would die, it is evident that they must 
have some source of heat in themselves. This 
is found in the union of the oxygen of the air 
breathed, with the carbonaceous matter eaten as 
food, and the formation of carbonic acid and 

IV II I II 

water (COo and H2O), just as in the case of the 
combustion of the wood in the grate. Only, in- 
stead of this union taking place in one spot, and 
so rapidly as to be accompanied by light, as in 
the case of the grate fire, it takes place in each 
drop of the fluid circulating in the body, and so 
slowly and continuously as not to be noticed- 
Nevertheless the chemical reaction seems to be 
identical. 



18 THE CHEMISTRY OF 

The first condition of animal life to be studied 
is, then, that portion of the food which supplies 
the heat necessary for the other chemical changes 
to take place. The class of foods which will be 
here considered as those for the production of 
animal heat, includes carbon compounds, chiefly 
composed of carbon, hydrogen, and oxygen. 

These carbonaceous bodies need abundance of 
oxygen for their slow combustion or oxidation, 
and hence the diet of the animal must include 
fresh air, — a point too often overlooked. It does 
not make a bright fire to pile on the coal 
without opening the draught. 

A certain quantity of heat is produced by other 
causes than this combustion of carbon compounds, 
which will be considered later, but the best 
authorities seem to now agree that the chief heat- 
producing foods used by the human race include 
starch, sugar, and fot. 

Starch is the first in importance, both from its 
wide distribution and its extensive use. Starch is 
found in all plants in greater or less abundance. 
It is laid up in large quantities in the seeds of 



COOKING AND CLEANING. 19 

many species. Rice is nearly pure starch, wheat 
and the other cereals contain sixty to seventy 
per cent of it. Some tubers contain it, as pota- 
toes, although in less quantity, ten to twenty per 
cent. It is formed from the carbonic acid gas 
and water contained in the air, by means of the 
living plant-cell and the sun's rays, and it is 
the*cnd of the plant life, the stored energy of the 
summer, prepared for the early life of the young 
plant another year. 

Common sugar, cane-sugar, is found in fruits 
and the juices of some plants. It is directly or 
indirectly a product of plant life. The chemical 
transformations of starch and sugar have" been 
very carefully and scientifically studied, with refer- 
ence to brewing and wine-making. 

Several of the operations concerned necessitate 
great precision in respect to temperature and 
length of time, and these operations bear a close 
analogy to the process of bread-making by means 
of yeast. The general principles on which the 
conversion of starch into sugar, and sugar into 
[ikohol, are conducted, will therefore be stated as 



20 THE CHEMISTRr OF 

preliminary to a discussion of starch and sugar as 
food. 

There are two distinct means known to the 
chemist, by which this change can be produced. 
One is by the use of acid and heat, which 
changes the starch into sugar, but can go no 
farther. The other is by the use of a class of 
substances called ferments, some of which #iave 
the power of changing the starch into sugar, and 
others of changing the sugar into alcohol and 
carbonic acid gas. These substances are in great 
variety, and the. germs of some of them are always 
present in the air. 

A substance is formed in sprouting grain which 
is called diastase, or starch converter, which first 
changes the starch into sugar or glucose, under 
the influence of warmth, as is seen in the pre- 
paration of malt for brewing. The principal 
chemical change is expressed by the following 
re-action : 

IV I II I II IV I II 

Cb H,o ©6 -f Hj O -I- ferment = Ce H,a Ob 
Starch. Water. Sugar (glucose). 

The sugar formed from starch is one of the 



COOKING AND CLEANING. 21 

class of sugars commonly called glucose. These 

sugars differ in some of their properties from 

ordinary cane sugar, but cane sugar is easily 
changed into glucose : 

IV I ' 11 I II IV I II 

C,,Hs2 0n + H, O + ferment = 2 C„ H,, Oa 
Cane Sugar. Water. Glucose. 

So, whether we start with starch or cane-sugar, 
glucose is produced by one kind of fermentation, 
and this glucose is then converted by yeast into 
alcohol and carbonic acid. In beer, the alcohol 
is the product desired, but in bread-making the 
chief object of the fermentation is to produce 
carbonic acid to puff up the bread, the alcohol 
escapes in the baking. 



IV I II 
2 Ca Ho O 
Alcohol. 
1 IV II 

Dextrose. 2 C Oj 



IV I II 

L/6 -1112 Oe = 



Carbonic Acid Gas. 

The alcohol, if burned, would give carbonic 
acid gas and water. 

IV I II II IV II I II 

2 Ca He O + 12 O = 4 C Oa -t- 6 Ha O 

Alcohol. Oxygen. Carbonic Water. 

Acid Gas. 

It will be seen that the total number of atoms 



22 THE CHEMISTRY OF 

of carbon remains constant. There are six in the 
starch, and 2+4=6 in the carbonic acid gas 
at the end, and but two atoms of hydrogen have 
been added, while 13 atoms of oxygen have been 
required; hence, 16 lbs. of starch will yield 
26 lbs. of carbonic acid gas and 10.8 lbs. 
of water, more than double the weight of the 
starch. These products of decomposition are 
given back to the air in the same fonii in 
which those substances existed from which the 
starch was originally formed. 

The same cycle of chemical changes goes on 
in the human body when starchy . substances are 
taken as food. Such food, moistened and warmed 
in the mouth, becomes mixed with air, by reason 
of the property of the sahva to form froth, also 
it is impregnated with ptyalin, a substance which 
can change starch into sugar, as can the diastase 
of the malt. The mass then passes into the stomach, 
and the change once begun, goes on. As soon as 
the sugar is formed, it is absorbed into the circula- 
tory system and is in some manner oxidized, 
changed into carbonic acid gas and water. 



COOKING AND CLEANING. 23 

No starch is used in the human system as such ; 
it must undergo this transformation into sugar be- 
fore it can be absorbed. Whatever of it passes out 
of the stomach unchanged, meets a very active 
converter in the pancreatic juice. If grains of 
starch escape these two agents, they leave the 
system in the same form as that in which they 
entered it. 

The cooking of pure starch as rice, farina, etc., 
requires httle explanation. The starch grains are 
prepared by the plant to keep during a season of 
cold or drought, and are very close and compact ; 
they need to be swollen and distended by moisture 
in order that the chemical change may take place 
readily, as it is a law that the finer the particles, 
the sooner a given change takes place. For in- 
stance, i)owdered alum will dissolve in water much 
sooner than a crystal of alum, or marble-dust in 
acid sooner than a piece of marble. Starch grains 
may increase in bulk twenty-five times in process 
of hydration. 

The cooking of the potato and other starch- 
containing vegetables, is likewise a mechanical 



24 THE CHEMISTRY OF 

process very necessary as a preparation for the 
chemical action of digestion ; for raw starch has 
been shown to require a far longer time and 
more digestive power than cooked starch. Little 
change can take place in the mouth when the 
starch is not heated and swollen, and in case the 
pancreatic secretion is disturbed the starch may 
not become converted at all. 

The most important of all the articles of diet 
which can be classed under the head of starch 
foods is bread. AVheat bread is not solely starch 
but it contains a larger percentage of starch than 
of anything else, and it must be discussed under 
this topic. 

Bread of some kind has been used by man- 
kind from the first dawn of civilization. During 
tlie earlier stages it consisted chiefly of powdered 
meal and water, baked in the sun, or on hot 
stones. This kind of bread had the 'same char- 
acteristics as the modern sea-biscuit, crabkers and 
hoe-cake, as fur as digestibility was concerned. 
It had great density, it was difficult to masticate, 
and the starch in it presented but little more 



COOKING AND CLEANING. 25 

surface to the digestive fluids than that in the 
hard compact grain, the seed of the plant. 

Experience must have taught the semi-civilized 
man that a light porous loaf was more digestible 
than a dense one. Probably some dough was 
accidentally left over, until fermentation had set in 
and the possibility of porous bread was thus sug- 
gested. 

The ideal loaf, light, spongy, with a crispness 
and sweet pleasant taste, is not only aesthetically, 
but chemically, considered the best form in which 
starch can be presented to the digestive organs. 
The porous condition is desired in order that as 
large a surface as possible shall be presented to 
the action of the chemical converter, tlie ptyalin 
of the saliva. There is also a better aeration in 
the process of mastication. 

Very early in tiie history of the human race, 
leavened bread seems to have been used-. This 
was made by allowing flour and water to stand 
in a warm place until decomposition had well set 
in. A portion of this dough was used to start 
fermentation in fresh portions of flour and water 



26 THE CHEMISTRY OF 

to be made into bread. This kind of bread had 
to be made with great care, lest lactic acid and 
other bodies, unpleasant to the taste, should be 
formed. 

Because of this disagreeable taste, and because 
of the possibility that the dough might reach 
the stage of putrid fermentation, chemists and 
physicians sought for some other means of ren- 
dering the bread light and porous. The search 
began almost as soon as chemistry was worthy 
the name of science, and one of the early 
patents bears the date 1837. A good deal of 
time and thought has been devoted to tlie per- 
fecting of unfermented bread ; but since the 
process of beer making has been universally 
introduced, yeast has been readily obtained, and 
is an effectual means of giving to the bread a 
pleasant taste. Since tlie chemistry of the yeast 
fermentation has been better understood, a change 
of opinion has come about, and nearly all scien- 
tific and medical men now recommend fermented 
bread. 

The chemical reactions concerned in bread raising 



COOKING AND CLEANING. 27 

are identical with those in beer making. To the 
flour and warmed water is added yeast, a sub- 
stance capable of causing the alcoholic fermenta- 
tion. The yeast begins to act upon the starch 
at once, .especially if the dough is of a semifluid 
consistency, but no change is evident to the eye 
for some hours, as the formation of sugar gives 
rise to no other products : 

IV I II I II IV I II 

C„Hu,05 + H, O = C„H.sO. 

Starch. Water. Sugar. 

But as soon as the sugar is decomposed into 
alcohol and carbonic acid gas, the latter product 
makes itself known by the bubbles which appear 
and the consequent swelling of the whole mass. 

, IV I II 

( 2C, H„0 

ly ^ U ) Alcohol. 



CbHioOs = 



IV II 



Sugar. J 2C O., 

^ Carbonic Acid Gas. 

It is the carbonic acid gas (carbon dioxide) 
which causes the sponge-like condition of the loaf 
by reason of the peculiar tenacity of the gluten, 
one of the constituents of wheat. It is a well- 
known fact that no other kind of grain will make 



28 THE CHEMIST R r OF 

as light bread as wheat. It is the right propor- 
tion of gluten (a nitrogenous substance to be 
considered later), which enables the light loaf to 
be made of wheat flour. 

The production of carbonic acid gas is the end 
of the chemical process, the rest is purely me- 
chanical. The kneading is for the purpose of 
rendering the dough elastic by a spreading out 
and thorough incorporation of the already fer- 
mented mass with the fresh flour. 

Another reason for kneading is, that the bubbles 
of gas may be broken up into as small portions 
as possible, in order that there may be no large 
holes, but only very fine ones, evenly distributed 
through the loaf, when it is baked. 

The temperature at which the dough should be 
maintained during the chemical process, is the 
most important point. A lesson can be learned 
from the distillers of spirit. The best temperature 
for the first stage of the alcoholic femientation 
is 70° to 75° F., the maximum is 82° to 90°. 
Above 90°, the production of acetic acid is liable 
to occur. ^ 



COOKING AND CLEANimT."^ 29 

IV I II 11 IV I II I II 

C, Hr. O + O, = C, H4 O^ + Hs O. 

Alcohol. Acetic Acid. 

The more dense the dough, the more yeast is 
needed. After the dough is stiffened by the fresh 
flour and is nearly ready for the. oven, the tem- 
perature may be raised to 160° or 165° F., the 
temperature of the beer mash. A quick change 
then occurs which is so soon stopped by the heat 
of the oven, that no time is allowed for souring. 

In the use of leaven, the lactic fermentation 
is liable to take place, because sour dough often 
contains a ferment different from ordinary yeast, 
and this produces a different set of reactions. 

The temperature should be carefully regulated, if 
light and sweet bread is desired. The baking 6f 
the loaf has for its object to kill the fermejit, 
to heat the starch sufficiently to render it easily 
soluble, to expand the carbonic acid gas and 
drive off the alcohol, and' to "form . a crust which 
shall have a pleasant flavor. The oven must be 
hot enough to raise the temperature of the inside 
of the loaf to 212° F. The most favorable tem- 
perature for baking is 400° to 550** F. 



30 THE CHEMISTRY OF 

The brown coloration of the crust, which gives 
a peculiar flavor to the loaf, is probably caused 
by decomposition due to the high heat. Some 
dextrine may be formed. One hundred pounds of 
flour are said to make from 126 to 150 pounds 
of bread. This increa.se of weight is due to the 
incorporation of water, very possibly by a chem- 
ical union, as the water does not dry out of the 
loaf as it does out of a sponge. 

The bread seems moist when first taken from 
the oven, and dry after standing some hours, but 
the weight will be found nearly the same. It is 
this probable chemical change which makes the 
difference, to delicate stomachs, between fresh bread 
and stale. A thick loaf is best eaten after it is 
twenty-four hours old, although it is said to be 
" done," when ten hours have passed. Thin biscuits 
do not show the same ill effects when eaten hot. 
The bread must be \vell baked in any case, in order 
that the process of fermentation may be stopped. 

The expansion of water or ice into 1700 times 
its volume of steam is sometimes taken advantage 
of in making snow-bread, water gems, etc. It 



COOKING AND CLEANING. 31 

plays a part in the lightening of pastry and of 
crackers. 

Air, at 70°, expands to about three times its 
volume at the temperature of a hot oven, 'SO that 
if air is entangled in a mass of dough, it gives 
a certain lightness when the whole is baked. This 
is the cause of the sponginess of cakes made with 
eggs. The viscous albumen catches the air and 
holds it, even when it is expanded, unless the 
oven is too hot, when the sudden expansion^ is 
liable to burst the bubbles and the cake falls. / 

As has been said, the production of the porous 
condition, by means of carbonic acid, generated in 
some other way than by the decomposition of 
starch, was the study of practical chemists for 
some years. Among the first methods proposed, 
was one undoubtedly the best theoretically, but 
very difficult to put in practice, viz., the liberation 
of carbonic acid gas from bi-carbonate of sodium, 
by means of muriatic acid. 

I I IV II II 

Na H C O3 4- H CI = 
Soda. Hydrochloric 

Acid. 

II I II IV 
= Na CI 4- Ha O • -f- C Oi, 



32 THE CHEMISTRY OF 

The difficulty lies in the fact that this libera- 
tion of gas is instantaneous on the contact of the 
acid with the soda, and only a skilled hand can 
mix the bread and place it in the oven without 
the loss of much of the gas. Tartaric acid, the 
acid phosphates, sour milk (lactic acid), vinegar 
(acetic acid), alum, all of which have been used, 
are open to the same objection. Cream of tartar 
is the only acid substance commonly used which 
does not liberate the gas by simple contact in 
the cold. It unites with soda only when heated, 
because it is very slightly soluble in cold water. 
For the even distribution of the gas by thorough 
mixing, cream of tartar would seem to be the 
best. The chemical reaction is shown in the table 
on page 49 But as,- beside gas, there are other 
products which remain behind in the bread, in 
the case of all the so-called baking powders, 
the healthfulness of these residues must be con- 
sidered. 

Common salt, the residue from the first-men- 
tioned reaction, is the safest, and perhaps the 
residues from acid phosphate are next in order. 



COOKING AND CLEANING. 33 

The tartrate, lactate, and acetate of sodium are 
not known to be especially hurtful. As the im- 
portant constituent of Seidlitz powders is Rpchelle 
salt, the same compound as that resulting from the 
use of cream of tartar and soda, it is not likely 
to be very deleterious, taken in the small quantities 
in which even habitual "soda-biscuit" eaters take 
it. 

The various products formed by the chemical 
decomposition of alum and soda are possibly the 
most injurious, as the sulphates are supposed to 
be the leasts readily absorbed salts. Taking into 
consideration the advantage given by the insolubility 
of cream of tartar in cold water, and the com- 
paratively little danger from its derivative, Rochelle 
salt, it would seem to be, on the whole, the best 
substance to add to the soda in order to liberate 
the gas ; but the proportions must be chemically 
exact, according to the reaction given. At least, 
there must be no alkali left, for a reason which 
will be given under the head of hindrances to 
digestion. 

Hence, baking powders prepared by weight 



34 THE CHEMISTRY OF 

and carefully mixed, are a great improvement on 
the teaspoonful measured by guess. The reactions 
of the various baking powders with the proportions 
of each will be given on page 49. 

Another group of substances which, by their slow 
combustion or oxidation in the animal body, yield 
carbonic acid gas and water, and furnish heat to 
the system, comprises the animal fats : as, for 
instance — suet, lard and butter ; and the vegetable 
oils, as ohve oil, the oily matter in corn, oats, etc. 

These fatty materials all have a similar compo- 
sition, containing when pure only carbon, hydrogen, 
and oxygen. They differ from starch and sugar 
in the proportion of oxygen to the carbon and 
hydrogen, there being very little oxygen relatively 
in the fatty group, hence more must be taken from 
the air for their combustion. 

CinHadOi Ce H|o O5 

Stearic Acid in Suet. Starch. 

One pound of starch requires one and two-tenths 
pounds of oxygen, while one pound of suet requires 
about three pounds of oxygen for perfect combus- 
tion. At the same time, a greater quantity of heat 



COOKING AND CLEANING. 35 

can be obtained from the fats, pound for pound, 
than from starch or sugar ; hence, people in Arctic 
regions require fat, 

A most noticeable difference between the starch 
group and the fat group, is that the latter is stored 
up in the system against a time of need. This is 
the more easily done, since the fats do not seem 
to undergo any essential change in order that they 
may be absorbed. They pass the mouth and stomach 
without any chemical change, and only when they 
encounter the bile and the other intestinal juices, 
is there any question as to what happens. 

With these fluids, the brie especially, the fats 
form emulsions in which the globules are finely 
divided and rendered capable of passing through 
the membranes into the circulatory system. The 
change, if any, is not one destructive of the proper- 
ties of the fatty matters. The globules are carried 
along by the blood, and deposited wherever needed, 
to fill up the spaces in the muscular tissue, and 
to serve as a reserve supply of fuel. 

There seems to be good reason for believing 
that the animal does derive some fat from the 



36 THi» CHEMISTRY OF COOKING, ETC, 

other constituents of its food, but it is not an 
important question in the diet of mankind, for 
even the rice eaters use butter or oil with their 
food. 

It must not be inferred from what has been said 
that the oxidation of starch and fat is the only 
source of heat in the animal body. A certain 
quantity is undoubtedly derived from the chemical 
changes of the other portions of food, but the 
chemistry of these changes is not yet fully under- 
stood. 



CHAPTER III. 

NITROGENOUS FOOD AND THE CHEMISTRY OF NUTRITION.- 

TN the previous chapter, the food necessary for 
the existence of the adult animal was con- 
sidered ; but animals do more than exist, they 
move and exert force, in mechanical terms they 
do work; also the young animal grows. 

For growth and work, something else is needed 
beside starch and fat. The muscles are the in- 
struments of motion and they must grow and be 
nourished, in order that they may have power. 
The nourishment is carried to them by the blood 
corpuscles. We find in these, as well as in mus- 
cular tissue, an element which we have not here- 
tofore considered, nitrogen. We find it also in the 
products of their decomposition, hence we reason 



38 THE CHEMISTRT OF 

that if the wear and tear of the muscles causes 
the liberation of nitrogenous compounds, which 
pass out of the system as such, this loss myst 
be supplied by the use of some kind of food 
which contains nitrogen. Starch and fat do not ; 
therefore they cannot furnish it to the blood. 

The typical food of this class is albumen, white 
of egg ; hence the terms albuminous and albuminoid 
are often used as descriptive of the group. The 
other common articles of diet containing nitrogen 
are the casein of milk, the musculine of animal 
flesh, the gluten of wheat, and the legumen of 
peas and beans. The proportion of the element 
in each is shown in the table on page 53. 

The chemical changes which these bodies un- 
dergo are not well understood. The nitrogenous 
food is finely comminuted in the mouth, because, 
as before stated, chemical action is rapid in pro- 
portion to the fineness of division ; but it is in 
the stomach that the first chemical change occurs. 

The agents of this change are the pepsin and 
the acid of the gastric juice ; the two together \ 
render the nitrogenous substance soluble and dia- 



COOKING AND CLEANING. 39 

lysable, capable of passing through the membranes. 
Neither seems able to do this alone, and it 
■does not seem to matter what acid is present so 
long as it is acid and just acid enough ; but if the 
acid is neutralized, action ceases ; hence the danger 
of soda biscuit with too much soda. 

The chemical changes which go on after the 
albumen is taken into the system are not known. 
A decomposition of some sort takes place, and the 
nitrogen passes out of the system in urea, being 
separated by the' kidneys, as carbonic acid gas is 
by the lungs. 

The effect of cooking upon nitrogenous food 
should be such as will render the substance more 
soluble, because in this case digestibility means 
solubility. Therefore white of egg (albumen) and 
curd of milk (casein), when hardened by heat, 
must not be swallowed in lumps. 

In the case of flesh, the cooking should soften 
and loosen the connecting tissue, so that the little 
bundles of fibre, which contain the nutriment, may 
fall apart easily when brought in contact with the 
teeth. Any process which toughens and hardens 



40 THE CHEMISTRY OF 

the meat should be avoided. The cooking of 
beans and all leguminous vegetables should soften 
and loosen the compact grains. Hard water should 
be avoided, as an insoluble lime or magnesia com- 
pound of legumen is formed. 

We have now considered the three classes of 
food under one or more of which all staple articles 
of diet may be placed — the starch food, the fats and 
the nitrogenous material. Some general principles of 
diet, indicated by science, remain to be discussed. 

One of the most obvious questions is : Which is 
best, — starch or fat, beans and peas, or flesh? 
As to starch or fat, the question has been answered 
by experience, and science has only tried to explain 
the reason. The colder the climate the more fat 
the people eat. The tropical nations live chiefly 
on starch foods, as rice. From the statements on 
page 50, it will be seen that this is right ; fat yields 
more heat than rice. Therefore the inference is 
plain that in the cold of winter fat is appropriate 
food, while in the heat of summer rice or some 
other starch food should be substituted. 

No such evident rule can be seen in the case 



COOKING AND CLEANING. 41 

of the albuminous foods. At most, the class can 
be divided into three groups. The first includes 
the material of vegetable origin, as peas, lentils, 
and the gluten of wheat. The second comprises 
the white of egg and the curd of milk, material of 
animal origin. The third takes in all the animal 
flesh used by mankind as food. 

Considering the question from a purely chemical 
stancHtJoint, without regarding the moral or social 
aspects of the case, two points stand out clearly : 
I St. If the stored-up vegetable matter has required 
tJie force derived from the sun to prepare it, the 
tearing apart, and giving back to the air and earth, 
the elements of which it was built up, will yield 
so much force to whatever tears it down ; but a 
certain amount of energy must be used up in 
this destruction. 2nd. If the animal, having accom- 
plished this decomposition of the vegetable, and 
appropriated the material, is killed, and the pre- 
pared nitrogenous food in the form of muscle is 
eaten by man, then no force is necessary to render 
the food assimilable ; it is only to be dissolved 
in order that it may enter into the circulation. 



42 THE CHEMISTRY OF 

The force-producing power is not lost ; it is 
only transferred to another animal body. Hence 
the ox or the sheep can do a part of man's 
work for him in preparing the vegetable food for 
vise, and man may thus accomplish more than he 
otherwise could. There is, however, another side 
to this question. Nearly all, if not all, j^oung 
animals live on food of animal origin. The young 
of the human race live on milk, but it has been 
found by experience that milk is not the best 
food for the adult to live upon to the exclusion 
of all else. It is not conducjve to quickness of 
thought or general bodily activity. 

This fact, with many others, leads us to the 
conclusion that mankind needs some vegetable 
food. Two other facts sustain this inference. The 
digestive organs of the herbivorous animals form 
fifteen to twenty per cent, of the whole weight 
of the body. Those of the carnivorous animals 
form five to six per cent., those of the human 
race about eight per cent. The length of the 
canal through which the food passes bears about 
the same relation in the three classes. A mixed 



COOKING AND CLEANING. 4^ 

diet seems to be indicated as desirable by every 
test which has been applied, but the propoEtions 
in which the vegetable and animal food are to be 
mingled, as well as the relative quantities of car- 
bonaceous and nitrogenous material which will give 
the best efficiency to the human machine are not 
so easily determined. 

Dietaries, based upon experience and chemical 
analysis, have been prepared for soldiers' rations, 
and for use in prisons. Many cook-books and 
most works ,on physiology give lists of quantities. 

One who has studied the question for years 
says : " Not only the age and occupation, but 
also the individuality of the person play an im- 
portant part in the regulation of diet, and decide 
not only the quantity but also the kind of the 
food, and the form in which it is to be taken . . 
For the proper assimilation of the nourishment and 
its complete effect in the organism, the food must 
be agreeable ; it must relish . . A supply of 
needful nourishment is not enough. Man requires 
yet more. He must find his food pleasing to the 
taste . . The boiling and roasting of food 



44 THE CHEMISTRY OF 

materials are operations wliich we find only among 
civilized people, and they have been developed 
with the advance of civilization. The whole art 
of cooking amounts to this : So to prepare the 
food that it will best answer its end." * 

The nutrition of the animal body, that is, the 
assimilation of the food taken, is dependent upon 
absorption. Absorption is dependent upon pre- 
vious chemical ]:)rocesses. These processes are 
contingent upon the secretions, the saliva, the 
gastric juice, etc. \ and it is a well-known fact 
that the flow of these liquids is, to a great ex- 
tent, under the control of the nerves. Whatever 
excites the nerves pleasantly, causes an abundant 
secretion of the chemical agents of food change. 
In this fact lies the secret of modern cooking, the 
judicious use of condiments. 

Pettenkofer (Konig, page 21) says of condi- 
ments : " I may compare them to the right use 
of lubricants for an engine, which indeed cannot 
replace the steam power, but may help it to a 

* Die menschlichen Nahrungs-und Genussmittel, von Dr. J. Ronig. 
Berlin, 1880. /. 100. 



COOKING AND CLEANING. 45 

much easier and more regular action, and besides, 
prevent quite naturally the wearing out of the 
machine. In order to be able to do this, one 
condition is absolutely essential : the lubricant must 
not attack the machine, it must be harmless " 

Cooking has thus become an art worthy the 
attention of intelligent and learned women. The 
laws of chemical action are founded upon the law 
of ' definite proportions, and whatever is added 
more than enough, is in the way. The head of 
every household should study the condition of her 
family, and tempt them with dainty dishes if that 
is what they need. If the ashes have accumulated 
in the grate, she will call a servant to shake them 
out so that the fire may burn. If she sees that 
the ashes of the food previously taken are clog- 
ging the vital energy of her child, she will send 
him out into the air, with oxygen and exercise to 
make him happy, but she will not give him more 
food. 

Nature seems to have made provision for the 
excess of heat, resulting from the oxidation of 
too much starch or fat, by the ready means of 



46 THE CHEMISTRY OF 

evaporation of water from the surface, this loss of 
water being suppHed by drinking in a fresh sup- 
ply, which goes, without change, into the circu- 
lation. The greater the heat, the greater the 
evaporatioft ; hence the importance of water as an 
article of diet must not be overlooked. For an 
active person, the supply has been estimated at 
three quarts per day. Water is the heat regulator 
of the animal body. 

While dangerous disease seldom seems to result 
from eating an excess of starch or fat, because 
the portion not wanted is rejected as so much 
sand, many of the most complicated disorders 
do result from an excess of nitrogen diet. 

The readiness with which such substances undergo 
putrefaction^ and the many noxious products to 
which such changes give rise, should lead us to 
be more careful ns to the quantity of food. 

A growing person needs about one part of 
nitrogenous food to four of starch and fat ; a grown 
person, one part nitrogenous food to five or six 
of starch and fat. A fair average ration per day 
is perhaps : 



COOKING AND CLEANING. 47 

Bread i lb. lo oz. 

Fat I to 2 oz. 

Rice (cooked) i lb. 

Flesh i lb. 

All processes of cooking and the use of all con- 
diments which hinder digestion should be avoided. 
Woody fibre or cellulose, as bran, irritates the 
digestive canal, and causes it to empty itself of 
the food before the chemical change is complete. 
An excess of sugar sometimes decomposes with 
the formation of acids which have the same effect. 

Tannin, tobacco, salt in excess, and alcohol, all 
harden the albuminous part of the food, and by 
this means hinder solution. 

Certain substances, as alcohol and coffee, lessen 
the amount of food needed for the time being. 

The fats all decompose at about 300° F., into 
various bodies, some of them exceedingly acrid 
and irritating to the mucous membrane of the nose 
and throat, and which must also prove offensive 
to the lining of the stomach. This is probably the 
reason why many people cannot bear food fried 
in ^ 



48 THE CHEMISTRY OF 

In counting the cost of the several articles of 
diet, not only the price per pound, but the digesti- 
bility must be taken into account. 

It has been found by experiment that of the 
total starch in rice less than one per cent, is 
rejected, while in potatoes nearly eight per cent, is 
not used. (See table, page 52). 

The cost of a diet which derives all the nitrogen 
from the animal kingdom has been estimated in 
Germany as 9.2 marks per day; while an entire 
vegetable diet, giving the same chemical con- 
struction, is given at 1.95 marks per day. This 
is a very evident reason why the working people 
of all lands (except America) Hve on vegetable 
food almost entirely. 



COOKING AND CLEANING. 49 



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THE CHEMISTRY OF 






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COOKING AND CLEANING. 



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52 THE CHEMISTRY OF 

Digestibility of some articles of food shown 
by the per cent, of the several constituents re- 
jected : 





Nitrogen. 


Fat. 


Starch Matter. 


Maize 


15-5 


17-5 


3-2 


Rice 


20.4 


7-1 


•9 


Potatoes 


32.2 


3-7 


7.6 


Macaroni 


17.1 


5-7 


1.2 


Yellow Beets 


39-0 


6.4 


18.2 


White Bread 


18.7 




^ 


Roast Meat 


2.5 


21. 1 




Eggs 


2.9 


5-0 




Milk 


7.0 


7-1 




Butter 


"•3 


2.7 




Bacon 


12. 1 


17.4 





It has been estimated (Moleschott) that a work- 
ing man needs daily 130 grms,* of nitrogenous 
food and 448 grms. of non-nitrogenous food, starch, 
fat, etc. 

The following table shows the weights of the 
different kinds of food which must be eaten in 
order that the required quantity may be obtained; 

* s8 gnns. = i ounce nearly. 



COOKING AND CLEANING. 



53 





For 




For 




130 grms. 

Nitrogenous 
Substances. 


448 grms. 

Non-nitrogenous 

Substances. 


Cheese 


338 


Rice 


572 


Lentils 


491 


Maize 


625 


Peas 


582 


White Bread 


631 


Beans " Acke 


r- 


Lentils 


806 


bohnen " 


590 


Peas 


819 


Ox Flesh 


614 


Beans "Acke 


r- 


Eggs 


968 


bohnen " 


823 


White Bread 


1.444 


Eggs 


902 


Corn 


1,642 


Rye Bread 


930 


Rice 


2,562 


Cheese 


2,011 


Rje Bread 


2.875 


Potatoes 


2,039 


Potatoes 


lO.CXX) 


Ox Flesh 


2,261 



Daily Rations in grms. 

Albuminous 
[(nitrogenous) Starch Mineral 

Food. Fat. Food. Salts. Water. 



Soldier's Ration 








(ordinary) 


119 


56 


48s 


Soldier's Ration 








(very rich) 


116 


209 


400 


Working Men 


148 


87 


526 



30 2858 

(Mean of estimates by 12 different authorities.) 



54 THE CHEMISTRY OF COOKING^ ETC. 

The daily need of a woman is counted as 
three-fourths or four-fifths that of a man. 



Elementary ( 


COMPOSl 


[TION IN 






< of C. 


H. 


0. 


N. 


s. 


Vegetable Albumen 53.1 


7.2 


20.5 


17.6 


T.6 


Egg " 534 


7.0 


22.4 


15-7 


1,6 


Flesh (Fowl) 53.18 


7.03 


.48 


15-75 


1-S6 


Casein (Curd of Milk) 53.5 


7-05 


.88 


15-77 


.8 



Of 100 parts of food (solid and liquid) taken, 
is discharged : 

By the Intestines 6.7 per cent. 

" " Kidneys 49.3 «' " 

" *' Skin and Lungs 42.6 " " 



PART II. 



CHAPTER I. 

THE CHEMISTRY OF CLEANING. 

"jVTEXT to the materials for food, those used for 
the very necessary operations of cleaning are 
perhaps of greatest interest to the housekeeper. 

This chapter will discuss the properties of the 
chemical substances which are suited to aid in 
performing the work of cleansing to the best 
advantage, 
.y/ First in importance among these chemical ma- 
terials are soap and its substitutes. 

" Whether the extended use of soap be preceded 
or succeeded by an improvement in any com- 
munity — whether it be the precursor or the result 
of a higher degree of refinement amongst the 
ss 



56 THE CHEMISTRT OF 

nations of the earth — the remark of Licbig must 
be acknowledged to be true, that the quantity of 
soap consumed by a nation would be no inaccurate 
measure whereby to estimate its wealth and civiliza- 
tion. Of two countries with an equal amount of 
population, the wealthiest and most highly civilized 
will consume the greatest weight of soap. This 
consumption does not subserve sensual gratification, 
nor depend upon fashion, but upon the feeling of 
the beauty, comfort and welfare attendant upon 
cleanliness ; and a regard to this feeling is coin- 
cident with wealth and civilization." * 

It is surely a problem of the greatest interest to ' 
every housekeeper, how to keep her household 
and its belongings in a state of cleanliness that ' 
shall be a state of perfect health ; for a large 
portion of disease is a direct result of uncleanly 
ways.. [The toleration of impure air in close rooms 
is one of the most common, as well as one of the 
most easily remedied of these uncleanly ways.] 

This state of cleanness must also be attained 
at the least cost in money, time and labor. Such 

• Muspratt's Chemistry as applied to Arts and Mattu/aciures. 






COOKING AND CLEANING. 57 

a question ought to stir the business capacity of 
every woman in charge of a house. As we have 
said, soap and its substitutes justly claim, first 
of all, our attention. 

Many primitive peoples find a substitute for soap 
in the roots, bark or fruit of certain plants. Nearly 
every country is known to produce such vegetable 
soaps, the quality whicli they possess of forming 
an eniulsio-n with oily substances being due to a 
peculiar vegetable substance, known as Saponin. 
Many of these saponaceous barks and fruits are 
now used with good results — the "soap bark" 
of the druggist being one of the best substances 
for dressing over black dress goods, whether of 
silk or woollen. 

The fruit of the Soapberry tree — Papindus 
Saponaria — a native of the West Indies, is said 
to be capable of cleansing as much linen as sixty 
times its weight of soap. 

Wood ashes were probably used as cleansing 
material long before soap was made, as well as 
long after its general use. Their properties and 
value will be considered later. 



58 THE CHEMISTRY OF 

Soaps for laundry use are chiefly composed of 
alkaline bases, combined with fatty acids. Their 
action is "gently but efficiently to dispose the 
greasy dirt of the clothes and oily exudations of / 
the skin to miscibility with, and solubility in wash 
water." * 

We may state it in this way. All kinds of 
cleansing, whether it be of our skins, our clothes, 
our painted wood -work, our windows or our dishes, 
consist of two distinct operations : first, the solu- 
tion or emulsion of the oily matter which causes 
the dust and dirt to adhere ; second, the mechan- 
ical removal of the dust and dirt, which, in most 
cases, is effected by water. Sometimes, as in the 
case of silver and paint, the cleansing agent is 
fine sand or chalk. 

It will readily be seen that the first operation — 
the removal of the oily matter — is of prime im- 
portance in the laundry. In order clearly to 
understand the question of the best means to 
secure this removal, we must first- consider the 



* Chemistry applied to the Manufacture of Soaps and Candles. 
Morfit. 



COOKING AND CLEANING. 59 

properties of the grease and oily matters, and next, 
what agents will dissolve them or form an emulsion 
with them. 

Oily matters in general are soluble in certain 1 
substances, as salt is soluble in water, and can be / 
recovered in their original form from such solutions 
by simple evaporation. Some of them readily 
combine with alkalies to form the kind of com- 
pound which we call soap. Others in contact with 
the alkalies form emulsions, so-called, in which the 
fatty globules are suspended, forming an opaque 
liquid. These emulsions are capable of being in- 
definitely diluted with clear water, and by this means 
the fatty globules are all carried away. The opacity 
of soap-suds is due to the fact that it contains 
particles in suspension, the nature of which will be 
presently shown. 

Setting aside the vegetable saponin, we have 
then two classes of agents which affect oily mat- 
ters, — the one class by simple solution, as turpen- 
tine, alcohol, ether, benzine, etc. ; the other class 
by a direft union, or by the formation of an 
emulsion. Agents of the latter class are substances 



60 THE CHEMISTRY OF 

known in chemistry as the alkali metals, and in 
order to justify the somewhat extended discussion 
of these alkali metals, we must remind our readers 
that the value of all soaps as detergents depends 
upon the alkali chiefly. To the distinguished 
French chemist, Chevreul, is due our knowledge 
of the action of soaps. 

"The neutral salts formed by the alkalies and the 
fat acids are decomposed by the water, whereby 
insoluble double fat acid salts, — stearates, palmi- 
tates, oleates — are separated, while the alkali is 
set free. By means of the free alkali the im- 
purities clinging to the materials are removed." 

Every woman must have noticed the peculiar 
opaque appearance of soap-suds, even before any- 
thing has been washed in it. This is due to the 
suspension in the water of the particles of these 
"insoluble double fat acid salts." 

[Hot water will dissolve soaps without this de- 
composition, but on cooling the separation takes 
place.] 

As each soap-maker claims that his product 
contains something which renders it better than 



COOKING AND CLEANING. 61 

Other soaps, or different from them, and as the 
chief stress in his recommendation rests on the 
fatty matters used, " Oil soap is superior to resin 
soap," and the hke, it behooves the housekeeper 
to remember that, within certain Hmits of course, 
the kind of fatty acid does not so much matter 
to her (provided only that it is not putrid or 
otherwise unfit for use) as the quantity and quality 
of the alkali, and as she is often called upon to 
believe that some new chemical has just been 
discovered which makes a far more efficient soap 
than the world has ^ever before seen, it may be 
instructive for her to follow our discussions of the 
alkali metals and their compounds. 

The chemical group of " alkali metals " com- 
prises six substances — Ammonium, Caesium, Lithium, 
Potassium, Rubidium and Sodium. Two of the 
six — Caesium and Rubidium — were discovered by 
means of the spectroscope, not many years ago, in 
the mineral waters of Diirckheim, and probably 
the total amount for sale of all the salts of these 
metals, could be carried in one's pocket. A third 
alkali metal — Lithium — occurs in several minerals, 



62 THE CHEMISTRY OF 

and its salts are of frequent use in the laboratory, 
but it is not sufficientl}^ abundant to be of com- 
mercial importance. 

As regards the three remaining alkali metals, the 
1 1 II -.^ 

hydrate of Ammonium, (NH4) HO, is known as ''Vola- ^ 

I I II 
tile Alkah," the hydrates of Potassium, KHO. and 

I I II 
Sodium, NaHO, as " Caustic Alkalies." With these 

three alkahes and their compounds, and tiiese alone, 
are we concerned in housekeeping. The volatile 
alkali, Ammonia, has been recently prepared in quan- 
tity and price such that every housekeeper may 
l/ccome acquainted with its use. It does not often 
occur in soaps, and its use is confined to the more 
delicate cleansing operations, the bath, the washing 
of woollens, and other cases where its property of 
evaporating, without leaving any residue to attack the 
fabric or to attract anything from the air, is invaluable. 
This property affords a safeguard against the care- 
lessness of the laundress in not sufficiently rinsing 
the fabric, and this imperfect rinsing is at the bottom 
of most of the trouble in washing woollens with 
soap or caustic alkah. All flannels worn next the 



COOKING AND CLEANING. 63 

skin, all the woollens of an infant's wardrobe, should 
be washed in water made soft and alkaline by 
ammonia, or ammonium carbonate. An additional 
advantiige will be found in the fact that the shrink- 
age of woollens thus washed is very slight. The 
ammonium compounds are somewhat more ex- 
pensive than the caustic alkalies, but in the present 
time, when an amnion iacal liquor is largely produced 
as a secondary product in the manufacture of coal 
gas, the cost is not excessive compared with the 
benefit its use confers. For use . in the bath, and 
for woollens, the ammoniacal gas liquor must have 
passed through a process of purification, in order 
to free it from some other products of the de- 
structive distillation of coal, which is not healthful 
or useful. This caution must be borne in mind, 
as a crude article is sometimes sold for ^eaning 
paint or carpets ; this is not fit for the uses we 
have been specifying. 

Ammonia water, bought of the best dealers in 
chemicals and druggists' supplies, costs about 30 
cents a pint, without the bottle. 

A pint of this liquid possesses as much alkaline 



64 THE CHEMISTRY OF 

1 IV II I II 

value as ten ounces of sal soda, Na2C03+ loHgO, 

and has not the injurious properties of the latter, 

even when used in excess. As the alkali is volatile, 

and water nearly boiling will retain only about one 

seventh as much of the ammonia gas as water at 

the ordinary temperature of the air, it will be seen 

that the directions on the various botdes of 

" Magical " washing fluids which contain ammonia, 

to pour the required quantity into hot water, with 

the word " hot " especially emphasized, are at 

variance with the known properties of this sub 

stance. The fluid should be largely diluted with 

cold water, and then added to the warm water. 

never to water too hot to bear the hand in. 

Ammonia is most excellent for cleaning glass 
(but not for brass, as it dissolves copper, and 
copper salts). 

A teaspoonful of ammonin, added to a quart 
of water, is the best possible agent for cleansing 
hair brushes. 

For use in travelling, the solid ammonium car- 
bonate is preferable ; for use in hard water it is 



COOKING AND CLEANING. G5 

also better, as the lime is precipitated out by it as 
by sal soda. It costs twenty-five or thirty cents 
a pound, and one pound of it is of as much 
alkaline v. due as two pounds of sal soda. 

Some compounds of the two alkali metals, Potas- 
sium and Sodium, are capable of saponifying fats 
and forming the complex substances known as 
soaps. 

For the » compounds of . these alkalies, employed 
in the manufacture of soap, we shall use the 
popular terms "potash" and "soda," as less likely 
tj cause confusijn in our readers' minds. Potash 
makes soft soap ; soda makes hard soap. Potash 
is derived from wood ashes, and in the days of 
oi.r grandmothers soft soap was the universal 
.detergent. Potash (often called Pearlash) was 
cheap and abundant. The wood fires of every 
household furnished a waste product ready for its 
extraction. Soda ash was, at that time, obtained 
from the ashes of sea-weed, and of course was 
not common inland. Aerated Pearlash (Potassium 
bicarbonate), under the name of saleratus, was used 
for bread. 



66 THE CHEMISTRr OF 

The discovery by the French manufacturer, 
Leblanc, of a process of making soda ash from 
the cheap and abundant sodium chloride, or com- 
mon salt, has quite reversed the conditions of the 
use of the two alkalies. Potash is now some 
eight cents a pound, soda ash is only three. 

In 1834, Mr. James Muspratt, of Liverpool, first 
carried out the Leblanc process on a large scale, 
and he is said to have been compelled to give 
away soda by the ton to the soap-boilers, before 
he could convince them that it was better than 
the ashes of kelp, which they were using on a 
small scale. But the soap trade, as we now know 
it, came into existence after the soap-makers real- 
ized the value of the new process. Soda ash is 
now the cheapest form of alkali, and housekeepers 
will do well to remember this fact when they are 
tempted to buy some new " ine," or "crystal." 

In regard to the best form in which to use tlic 
alkali for washing purposes, experience is the best 
guide, — that is, experience reinforced by judgment ; 
for the num.ber of soaps, and soap substitutes, in 
the market is so great, and the names so little 



COOKING AND CLEANING. 67 

indicative of their value, that only some general 
information can be given. 

In the purchase of soap, it is safest to choose 
the make of some well-known and long-established 
firm, of which there are several who have a repu- 
tation to lose if their product is not good ; and, 
for an additional agent, stronger thart soap, it is 
better to buy sal soda (sodium carbonate) and 
use it knowingly, than to trust to the highly lauded 
packages of the grocery. A pound of sal soda 
contains from four to five times as much alkali as 
a pound of hard soap, and therefore it should 
be used with care. 

Washing soda should never be used in the solid 
form, but should be dissolved in a separate vessel, 
and the solution used with judgment. The inju- 
dicious use of the solid is probably the cause of 
the disfavor with which it is so often regarded. 
One of the most highly recommended of the scores 
of " washing compounds " in the market, doubtless 
owes its popularity to the following directions : 
"Put the contents of the box into one quart of 
boiling water, stir well, then add three quarts of 



68 THE CHEMISTR T OF 

cold water : this will make one gallon. For washing 
clothes, allow two cupfuls of liquid to a large tub 
of water." 

As the package contains about a pound of 
washing soda, this rule, which good housekeepers 
have found so safe, means aJDOut two ounces to a 
large tubful of water, and this in solution. 

Ten pounds of washing soda can be purchased 
of the grocer for the price of this one-pound 
package, with its high-sounding name. Nearly all 
the compounds in the market depend upon washing 
soda for their efficiency. Usually they contain 
nothing else. Sometimes soap is present and, 
rarely, borax. In one or two, ammonia has been 
found. 

For hard water, a little sal soda is almost indis- 
pensable. Borax is a very good cleansing agent 
for many purposes. The sodium is in a milder 
form than in washing soda. For delicate fabrics 
and for many colored articles, it is the safest 
substance to use. 

On first thought, we may wonder why we need 
to add these chemical agents to soap, when our 



COOKING AND CLEANING. 69 

grandmothers did without them ; but we must 
remember that our grandmothers used soft soap 
and wood ashes for all the cleansing operations 
for which we now depend upon hard soap. It is 
a recognized fact that soft soap is much more 
caustic and hence more effective in removing 
grease than hard soap. The reason for this lies 
partly in the fact that the gelatinous character of 
the soap allows a considerable proportion of free 
lye to be mechanically held in the mass, and partly 
because potash is a more powerful chemical agent 
than soda. 

Many prudent housewives still make soft soap 
for their own use. Many more add to the effi- 
ciency of the common soap by dissolving several 
pounds of it in hot water, adding about one-third 
as many pounds of sal soda, and allowing the 
mass to cool into a white, soft curd. 

A washing fluid, said to be of great value, is 
prepared by the addition of freshly slaked lime to 
a solution of sal soda. When the liquid has 
become clear, alcohol is added to it, and it is 
bottled for use. 



70 THE CHEMISTRY OF 

II I II 
Slaked lime, CaH202, or caustic lime, and car- 
I II 
bonate of soda, Na2(C03), put together in solution, 

II II 
must inevitably result in carbonate of lime, Ca(C03), 

I I IF 

and caustic soda, 2NaH0, — a compound much 
more dangerous to use in excess than sal soda. 
The alcohol dilutes this caustic solution, and the 
little gill cup used to measure the fluid for use, 
insures safety. The mistress who considers herself 
cautious will sanction the use of this "fluid," when 
she will not allow sal soda to be used. 

Turpentine has been sometimes recommended as 
an addition to washing fluids, but its use may be 
attended with danger, as, when applied in hot 
water, to the bare arms of the laundress, it is 
readily absorbed, and is liable to cause illness. 

There is a compound of sodium of great value 
for laundry and common use, which seems to take 
the place of the old-time soft soap. This is sodium 
silicate, water-glass, or soluble glass. It is manu- 
factured for print works, and its common name is 
"water-glass," that is, glass soluble in water, and 
free from the lime or lead of the common w^indow- 



COOKING AND CLEANING. 71 

glass. Being made from clean materials, sand and 
soda, or potash, it has no reminder of the dead 
meat or bone-boiler's establishment, as soap some- 
times has. The affinity of the alkali for the silica 
is not strong, and yet it holds until some stronger 
acid comes in contact with it. By virtue of this 
property, it is said by the few housekeepers who 
have hitherto had access to it, not to injure the 
fabric, even if used in excess, and to give to 
linen the clean, fresh appearance of new cloth. 
It is hoped that an agent so valuable to the 
housekeeper may soon be accessible to all. 

The removal of spots from clothing is a subject 
which has perplexed every woman. 

The fabrics upon which we wish to operate are 
nearly all colored, and the modern dye is such a 
complex and unstable compound that disaster is 
not uncommon. 

.Chloroform, ether, alconol, benzine, turpentine, 
all dissolve grease, but all are liable to show an 
enlarged ring if not very carefully applied, and the 
water in ethef and alcohol affects many colors. 
Turpentine is useful for some coarser fabrics, but 



72 THE C HE MI ST R V OF 

for the most delicate silks and woollens benzine 
or naphtha is the safest, not injuring the color, and, 
if pure, completely volatile. 

For grease on carpets or other articles, where 
washing is out of the question, absorbents may 
be used : such as powdered soapstone, magnesia, 
buckwheat flour, etc. 

These absorbents are also sometimes used to 
remove spots other than those caused by grease. 

Grass stains often baffle the best laundress. A 
sure, if expensive, solvent for chlorophyl (the green 
coloring matter of plants) is alcohol, if applied 
while the stain is still fresh. Fruit stains are generally 
removed by the well-known process of pouring 
on boiling water. In some cases oxalic acid is 
better. 

Red iron rust is most readily soluble in muriatic 
acid, and if one has a little knowledge of chemical 
principles, this acid may be of great use in the 
laundry. It is very readily washed out with clear 
water, and it does not affect most fast colors. As 
the iron compound formed is also soluble, it can 
be taken away entirely. The efficacy of salt with 



COOKING AND CLEANING. 73 

lemon is probably due to the setting free of a small 
amount of muriatic acid. 

Black iron stains, as those from the inks made 
with iron, may be best removed by oxalic acid, 
although it has little effect on red iron stains. 
The iron forms a colorless compound with the acid 
but great care must be taken to remove all of it by 
a thorough washing. The difificult solubility of oxahc 
compounds makes this harder. It is., well to 
wash the article with ammonia water finally, in 
order to remove the last traces of acid. Oxalic 
acid and ammonia are two of the" most useful 
agents in the laundry. For further details, see 
chapter II. 

It may comfort some young housewife to know 
that mildew is beyond the art of the chemist. It 
seems to be a vegetable growth, which attacks 
the cotton fibre, and in a measure destroys it, as 
dry rot does a stick of timber. If it is superficial 
only, successive washings and bleachings in the 
sun will remove it. If deep seated, its removal is 
hopeless ; as in other cases, prevention is the best 
cure. Some cloth is very liable to mildew, and 



74 THE CHEMISTRY OP 

servants are often blamed for its appearance without 
good cause. 

We will now consider some of the preparations 
for the mechanical removal of " matter in the wrong 
place" — tarnish on silver, spots on paint, etc. 

The matron of fifty years since, took care of her 
silver herself, or superintended the cleanmg verv 
closely, for the heirlooms were precious, or the 
gifts of friends valuable. The silver was hardened 
by a certain proportion of copper, and took a polish 
of great brilliancy and permanence. The matron 
of to-day, who has the same kind of silver, and 
who takes the same care, is the exception. Plated 
ware is found in nearly every household in our 
villages. The silver deposited from the batter\' 
is only a thin coating, and is of pure, soft metal — 
very bright when new, but easily scratched, easily 
tarnished, and never again capable of taking a beautiful 
polish. The utensils, being of comparatively little 
value, are left to the table-girl to clean, and of course 
she uses the material which will save her labor. 

In order to ascertain if there was any foundation 
for the prevalent opinion that there was mercury 



COOKING AND CLEANING. 75 

or some equally dangerous chemical in the silver 
powders commonly sold, we have purchased sam- 
ples in Boston and vicinity, and in New York and 
vicinity. 

Thirty-eight different kinds have been found. 

Of these, 

25 were dry powder. 
10 " partly liquid. 
3 " soaps. 

Of the twenty-five powders, fifteen were chalk 
or precipitated calcium carbonate, with a little 
coloring matter, usually rouge. 

6 were diatomaceous earth. 
2 " fine sand entirely. 
2 " " '^ partly. 

Mercury was found in none. No other injurious 
chemical was found in any save the "electro-plating 
battery in a bottle," which contained potassium 
cyanide, KCN, a deadly poison ; but it was labelled 
])oison, although the label also stated that "all salts 
of silver are poison when taken internally. This 
preparation does contain silver, and does deposit a 
thin coating, but it is not a safe article. 



76 THE CHEMISTRY OF 

Of the nine polishes, partly liquid, five contained 
alcohol and ammonia for the liquid portion ; four, 
alcohol and sassafras extract. The solid portion, 
in all cases, was chalk, with, in one case, the 
addition of a little jeweller's rouge. 

The caution to be observed in the use of these 
preparations is in regard to the fineness of the 
material. A few coarse grains will scratch the 

II IVII 

coating of soft silver. Precipitated chalk, CaCOa, 

IVII 

or well-washed diatomaceous earth, Si02, seem to 
be of the most uniform fineness. 

We may learn a lesson in this, as well as in 
many other things, from the old-fashioned house- 
wife. She bought a pound of whiting for twelve 
cents, floated off the fine portion, or sifted it 
through fine cloth, and obtained twelve ounces of 
the same material, for three ounces of which the 
modern matron pays twenty-five or fifty cents, 
according to the name on the box. 

Silver is liable to tarnish from many causes, some 
of which can be avoided. Flannel is apt to con- 
tain sulphur, and should not be used to wrap up 



COOKING AND CLEANING. 77 

silver articles. Clean, soft tissue paper first, then 
a bag of Canton flannel, form a good covering. 
Want of sufficient ventilation in a house shows 
itself very quickly by the tarnish on the silver, 
caused by foul air and coal gas. 

Iron and steel oxidize in damp air, according 
to the rule that the presence of water favors 
chemical change. A little oily coating will exclude 
the air and hence no oxidation can ensue. 

The mechanical removal of spots on paint and 
kitchen utensils is effected by scouring agents, 

II IV II II IV II 

such as chalk, CaCOa, whiting, impure CaCOj, 
pumice and Bristol brick (silicates), fine sand 

IV II 

Si02, and preparations which owe their cleansing 
properties to one of these solids. 

A frequent source of annoyance is the bluing, 
which seems to be indispensable to the city laun- 
dress, who has not fresh grass, or the white snow 
of the country on which to whiten her clothes. 

Three substances are at present used for this 
purpose. Indigo, from the plant Indigo tinctoria, 
has been known from time immemorial. Soluble 



78 THE CHEMISTRY OF ' 

Prussian blue, a chemical compound containing 
iron, is a recent invention. Ultramarine, the third, 
is a silicate, insoluble in water, giving a tint by 
means of the very fine blue powder, which is im- 
pacted in the cloth. 

The indigo bags of olden time have been almost 
entirely replaced by numerous " Soluble Blues," 
all of which are Prussian blue of greater or less 
strength. 

It must be borne in mind that this substance is 
decomposed by the fixed alkalies, and if the clothes 
are not rinsed free from soap-suds or washing 
soda, mysterious iron-rust spots may appear on 
the linen, caused by the decomposition of the 
bluing. The general yellowish tint, which is so 
often seen on linen, is probably due to this cause. 

Of fifteen different kinds of bluing which were 
examined, not one was anything but Prussian blue. 
Here, as in so many other cases, the young house- 
keeper who has had some training in a chemical 
laboratory, has an advantage over one who has not, 
in her idea of absolute cleanliness, and her con- 
ception of the inexorable laws of chemical change. 



(COOKING AND CLEANING. 79 

A long chapter might be written on the subject 
of economy in the case of the multitude of chemical 
preparations so freely offered for sale. There is 
so much for the young housewife to do that she 
is tempted by every promise of making labor easier, 
and is very ready to try anything that is 
recommended. 

She thinks that if her servants are provided with 
all the modern appliances for doing work quickly 
and well, it is their fault if they do not ac- 
complish it. She forgets that the past generation 
of women, who succeeded in keeping their familico 
healthy and happy, brought brains to the work ;i 
they knew, too, the properties of the substances i 
they used, because they prepared them at home. 

When American girls will learn to apply Chem- 
istry and Physics to every-day life, we may hope 
for a speedy solution of the servant-girl ques- 
tion. 



CHAPTER II. 

CHEMICALS FOR HOUSEHOLD USE. 

I . Adds. 

nPHERE are three acids which should be found 
in every laundry cupboard: acetic acid, 

IV 1 II II 

C2H4O2 ; muriatic or hydrochloric acid, H CI; and 

IV I II 

oxalic acid, C2H_04. 

Vinegar can be used in many cases instead of 
acetic acid ; but vinegar contains coloring matters 
which stain delicate fabrics, and it is better to 
use the purified acid, especially as the so-called 
vinegar may contain sulphuric acid. 

If soda has been spilled on black silk an ap- 
plication of acetic acid will usually restore the 
color. 
to 



THE CHEMISTRY OF COOKING, ETC. 81 

Many of the bright blue flannels and other 
fabrics found at the present time in our markets 
owe their brilliant shades to an acid compound of 
a coal-tar color, and as soon as they are washed 
in soap or ammonia, the alkali neutralizes the 
acid, and the color becomes pale and faded in 
appearance. If acetic acid or vinegar is added to 
the second rinsing water, the bright color is in all 
such cases restored. This fact was discovered by 
accident, and is well worth remembering. Of 
course, not all shades of blue are made with this 
compound, and hence not all faded blues can be 
thus restored. It is well to test a bit of the 
cloth before washing the whole garment. 

A weak acid like acetic acid is safe to use on 
many fabrics which would be injured by a strong 
acid. 

Muriatic or hydrochloric acid is useful in a 
multitude of ways. By means of it, the writer 
once restored, in a few minutes, a delicate blue 
cambric dress, which had been quite ruined by nu- 
merous large stains of red iron rust. The cloth was 
laid over a large bowl half filled with hot water, 



and the spots thus steamed were touched with a 
drop of the acid, and as soon as the iron was 
dissolved, the cloth was plunged into the water to 
prevent injury to the cotton fibres. All the spots 
were thus dissolved ofif; the garment was then 
quickly rinsed in several waters, and finally in water 
containing a little ammonia, which neutralized any 
trace of acid still remaining. This process is by 
far the best for removing red iron stains from 
white cloth. 

Porcelain or china, stained with iron, can be 
■ cleaned with muriatic acid. For the porcelain or 
enamelled water-closet basin it is especially useful, 
but the acid must be removed by rinsing with 
water followed by a little alkali to save the iron 
pipes below. 

The acid must not be used on marble, as it 
dissolves it with great rapidity, and the polish is lost. 

The property which muriatic acid, in common 
with the so-called stronger acids, possesses — that of 
liberating carbonic acid gas with brisk effervescence 
from its compounds, renders this acid valuable for 
the detection of carbonates. 



COOKING AND CLEANING, 83 

For instance, if the label of a washing powder 
claims it to be something new, and requires that 
it be vised without soda, as soda injures the clothes, 
it can be tested as follows : Put half a teaspoonful 
of the powder into a tumbler, add a little water, 
then a few drops of muriatic acid. A brisk effer- 
vescence will prove it to be a carbonate, and if 
tl.e edge of the tumbler is held near the colorless 
flame of an alcohol lamp, the characteristic yellow 
color of sodium will complete the proof. If the 
acid is added drop by drop until no more effer- 
vescence occurs, and there remains a greasy scum 
on the surface of the liquid in the tumbler, the 
compound contains soap as well as sal soda, for 
the acid unites with the alkali of the soap and 
sets free the grease. 

If some very costly silver polishing powder is 
offered as superior to all other powders, a drop 
or two of muriatic acid will decide whether or not 

II IV II 

it is chalk or whiting (CaCOs) by the efferves- 
cence or liberation of the carbonic acid gas. 

Oxalic acid is purchased in white crystals, 
and for use a saturated solution is made j as one 



S4 THE CHEMlSTRr OF 

part of it dissolves only in several parts of water, it 
is well to keep an excess of the crystals in the bottle. 
It is somewhat poisonous, and should not be left 
in the solid form within reach of careless people. 
A small bottle of liguid can, however, be kept 
with other laundry articles. 

This acid is the only efficient means which is 
known to the writer, for removing the shoe- 
leather stains from white stockings. It will take 
out most fruit stains on napkins and from the 
fingers ; for the latter purpose tartaric acid will 
also serve. 

Oxalic acid is invaluable to the housekeeper 
as a means of removing black iron stains, such as 
those caused by the iron inks. 

It is a more powerful acid than acetic acid, 
and must be carefully removed from cloth by 
rinsing with water and finally by ammonia. 

Oxalic acid is very efficient as an agent for 
cleaning brass, and seems even safer to use than 
acetic, as the compound of the latter with copper 
salts is one of the most dangerous of the copper 
compounds. 



COOKING AND CLEANING. 85 

IV n 
Sulphurous acid gas (SO2) is obtained by burn- 
ing sulphur, and is the well-known agent for 
bleaching. It will often remove spots which noth- 
ing else will touch. The cloth or other substance 
should be moistened and held over a bit of burning 
julphur ; as the agent is an acid, the same pre- 
cautions must be observed as in the case of the 
other acids, as to the removal of the Corrosive 
substance. 

2. Alkalies. 

The uses of ammonia water and ammonium carbon- 
ate, have been considered in the text ; a precaution 
to be taken is, chat the bottles should not be kept 
with other bottles containing liquids for internal use, 
as distressing accidents have occurred from swallow- 
ing ammonia. 

Caustic soda or potash is better for greasy tins 
than soap; a swab should be used to apply it, 
however, as it is corrosive to the hands. Silicate 
of soda may also be used for this purpose. 

Some alkali should be always at hand. The 
alkali compounds, sodium carbonate (sal soda) 



8G THE CHEMISTRr OF 

I IV TI I II IT IV II 

NagCOs + H 10 HjO and calcium carbonate CaCOg, 

are of daily use as has been already explained in 

the previous chapter. 



BOOKS FOR REFERENCE. 

^ 

For Teachers : 

"History of Chemical Theory." 

A. Wurtz. 
Translated and edited by Henry Watts. 

" Elementary Manual of Chemistry." 

Eliot and Storer. 

"Physiology and Hygiene." (Chapter on Digestion.) 

Huxley and Toumans. 

"Treatise on Chemistry." 

Roscoe and Sckorlemmer. 

For General Readers : 

" Elements of Chemistry.'* 

l^ Roy C. Cooley, 



COOKING AND CLEANING. 87 

"The Birth of Chemistry." 

Rodiuell. 

" Chemistry of Common Life." 

Johnston and Church {neiv edition), 

"The New Chemistry." 

5^. P. Cooke. 

"Lessons on Elementary Chemistry." 

Henry E. Roscoe. 

" Fermentation." 

• Schlitzenberger. 

" Vortrage uber die Entwickelungsgeschichte der Chemie 
in den letzten Hundert Jahren." 

Dr. A. Ladenburg. 



Table of some common elements with their atomic 
weights and symbols. 

NAME. SYMBOL. 

I 

Hydrogen H 

I 
Chlorine CI 

I 
Sodium Na 

I 
Potassium K 

I 
Silver Ag 

II 
Oxygen O 

II 
Copper Cu 



ATOMIC WRIGHT. 


I. 


35-5 


23- 


39.1 


108. 


16. 


63-4 



88 



THE CHEMISTRT OF COOKING, ETC. 



NAME. SYMBOL. 

II 

Calcium Ca 

Barium Ba 

II 
Lead Pb 



III 
Gold Au 



III V 

Nitrogen N or N 

III V 
Arsenic As or As 



ATOMIC WEIGHT. 
40. 

137. 
207. 



Zinc Zn 65.3 

III 
Boron B 



II. 

197. 



27.4 



II IV 

Iron Fe or Fe 56 

II IV 

Alurninum Al or Al 

II IV 

Tin Sn or Sn 118. 

IV 
Silicon Si 38. 

IV 
Carbon C 



13. 

14. 

75. 



INDEX. 



Page. 
Absorption of Food, ... 44 

Aceiic Acid, 80 

.Acids : 

Acetic, ... ... 80 

Hydro-cliloric or Muriatic, 80 

Oxalic, vy^'o 

Tartanc, 4q 

Acid Phosi.ha;e, 40 

Albumen, ...... 3S 

Albiimimius Food, .... ^ 1 

Alcoh'il, 2;-59-7i 

Alkalies, ^1; 

Caustic, 62 

Volatil.' 62 

Alum .^3-49 

Ammonia, 61-63-64-S5 

Ammonium Carbonate, . 63-''4-S5 

Assunilatinn, 44 

Atomic Weight ^ 

Baking Powders, ... . 32 49 

Benzire, ST7^ 

Billing, 77 

Mooks for Reference, ... 8'i 

Borax fis 

liread, 2\ 

F'ermented j'S 

Reason for Kneading. . z-i 
Temperature for Fe'n:eiit- 

ing 2S 

Temperature for Baking, 29 

Snow Bread 30 

Soda-Bread, .... 31-32-3? 
Carbonic Acid Gas, . . . 27 31-40 

Ca;sium 61 

Chemical Change, .... 1-16 

Element, 3 

Equation 11 

Reaction, ii 

Chloroform, 71 



Pagb. 

Cleaning : 

I'rass, 84 

Brushes, 64 

Gia^s, 64 

Paint 64 

Silv r, 74-75 

Cookine ' . . 4^ 

OfStirch, 23 

Of Niircgenous Food, . 39 
Cdst of N tro;;unous and Vege- 
table I >iet in Germany 

compared 4S 

Cream of T.irtar, 32-49 

D uger : 

Act tic -Vcid on Cupper, . 84 

Ani'Tionia, S5 

" B.I Icry in a Bo tie,"' . 7; 

Hard water, ' 40 

Soda I'j 

'J'utpnline in Washing, . 70 

Diastase, 20 

Etlier, 59-7' 

Fats. 34-35 

Decompiisition of . . . 4/ 

Fruit Stains, 72 

Glucose, 21 

Gluten, 27 

(Srass Stains, 72 

( Ircase on Carpels, .... 72 
Growth Nitrogenous Food re- 
quired for, 37 

Heat — Artificial, 16 

Source of in Animals, . 17 

Hea -proiiucirig Fond, ... 18 

Ink Stairs, 73 

Iron, niacin Stains of . . 73-82-84 
Rust, ...... 72-78-81 

Law of Definite Proportion l^ 

Weight, 13 



00 



INDEX. 



Page. 

Lime 70 

Lithium 61 

Magical Wasliing Fluids, . . 64 

Milflew, 73 

Milk 42 

MutitticAcid 81 

Ni'ropen, 37 

Percepiageof in Food, . 50-53 
Required in Growth and 

Work 37 

Oils 34-35 

Ox:\l:c Acid 83 

Pearl Asli, 65 

Plate Powderf, 75 

Pota>h, 65-85 

Potassium, 61 

Pttassium Cyanide, .... 75 

Princ pies of I >iet, .... 40 

Pripenies of Substances, . . i 
Proportion of Nitrogenous 

Food required, ... 46 

Ptyaliii ill Saliva 22 

Relation of Climate to Food, 40 
Removal of Spots, . . . 71-72-85 
Residues from Baking Pow- 

d>rs, 32-33 

Restoring Color, .... 80-81 

Roclielle Salts, 49 

Rubidium, 61 

Rust of Iron, 72-81 

Sal Soda, 65-67-85 

Salt, 32-47 

Saponin 57 

Silver-Tarnish, 74 

Snow-bread 30 

Soap, S5-58 

Bark t 57 

Berry Tree, 57 

Soda - . . 33-49-J'S 

Soda Ash, 6b 

Soda Bread 31-32-33 

Sodium, 61 

Carbonate, 67 

Silicate 70 

Soft Soap, 69 



Page. 

Soluble Glass 70 

Stains 71-72-80-82-84 

Starch, iS 

Chemical Changes of . . 20 

Cooking of 23 

Sugar 20 

Tabli^s: 

1. Atomic Weights, . 5 
II. ExLhangeab c Val- 
ues, 7 

III. Interchangeable 

Values, ... 9 

IV. Mineral Acids, . . 14 
B.ik ng Powders ... 49 
Composition of Some Ani- 
mal Food, 50-54 

Comrosiiicpu of Some 

Veget.ble Food, . . 51-54 
Comparative Digestibility 

of Food 52 

Daily Weight of Food 

Required 53 

Percentages of Waste, . 54 

Tannin, 47 

Temperature for Ferme.iting 

Bread, 28 

For Baking Bread. . . 29 

Tests witli Muria.ic Acid, . 83 

Tobacco, 47 

Turpentine, _ 59-70-71 

Trai:sfer of Force- Producing 

Power, 42 

Unit of Value, 6-7 

Vinegar, 80 

Volatile Alkali 67 

Yeast, 27 

Yellow Tint on Linen, ... 78 

Washing Fluids 69-70 

Washing Woollens 62-63 

Water as the Htat-Regulator 

of the Body, .... 46 

Water Glass, 7° 

Wood Ashes, 57-59 

Work, Nitrogenous Food Re- 

■ quired for 37 



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